Ozone has been conventionally used for sterilization, deodorization, bleaching, and so on. Ozone is a powerful oxidizing agent, and so its concentration needs to be controlled. Ozone concentration meters for measuring ozone concentration have thus been developed. For example, a light-absorption ozone concentration meter described in Patent Literature (PTL) 1 measures ozone concentration by irradiating a sample cell containing a sample with ultraviolet light and detecting the intensity of light transmitted through the sample cell.